After 3 years I think you should expect questions more on writing optimized and manageable code. Also if I were the interviewer, I would expect you to know a lot of other things in addition to servlets and JSP like Hibernate, sitemesh, tiles (if your 3 years experience is in web development)...

I am surprised,shocked and curious to know on what basis you are telling this??
I am learning Servlets and Jsp now and i dont know anything other than these in Java platform . i mean to say i dont know things like EJB or structs or hibernate or... . And i am expecting to move to java platform by learning servlets and jsp....
So your statement is kind of discouraging my plans :(

If Web Technologies (Servlets, JSPs etc) are all that you worked on then interviewer would expect you to be very proficient at it.

Forget about the sample questions. Do the following and you'd clear probably 90 % of interviews on web technologies :
1. If you havent already done it, then do consider an SCWCD. The certification would add little value but you'd read up about a lot of stuff that you'd rarely work on.
2. Download and read Servlet spec(2.4 would be fine), JSP Spec (2.0), EL spec etc
3. Check out the DTD for web.xml and explore each of the tags
4. Be familiar with JSTL tag library - esp core and format
5. If you arent familiar with custom tags yet, its time to learn writing custom tags
6. Brush up HTTP protocol basics, standard headers, standard eror codes etc - I have come across some candidates who do web development but dont understand basics of HTTP

reading up all this would barely take a month or so and once you are thoroughly done, you'd crack most of mid level positions for web developers

I just meant that I literally haven't been asked a question about servlets for a long time (except for one place where they were looking for a canned set of answers, which meant I wouldn't want to work there). The questions I'm most often asked are about specific frameworks ("How does Struts process a request?" and that kind of thing) rather than at such a low level.

That may also be influenced by my relative seniority and the kinds of positions I've interviewed for.

So don't be discouraged--you definitely need to understand how servlets, JSPs, and the basic request cycle works. You might be asked questions about some of the low-level objects (like what represents a request from a web browser, where do you store application- and session-specific data, and so on).

Anything built on top of the low-level web app components still requires an understanding of what's going on "under the covers".

There's a difference based on the type of position. I would be less likely to ask Dave a servlet question directly because I could use it as an assumption in ask a more advanced question. If I am interviewing a college student, I am going to ask the basics. For three years, it depends on what one has done during that three years.